1. Field of the Invention
The present invention relates to a golf club head and, more particularly, to a technique of improving an impact sound.
2. Description of the Related Art
In hollow golf club heads typified by a driver head, the head volume is increasing each year, so the crown and sole portions are getting thinner, and their areas are increasing along with this trend. Under the circumstance, a low-pitched impact sound is more likely to be generated at the time of striking a golf ball, so golfers who prefer high-pitched impact sounds want golf club heads which generate higher-pitched impact sounds. Hence, Japanese Patent Laid-Open Nos. 2002-186691 and 2003-102877, for example, disclose techniques of improving an impact sound by providing a rib in the sole portion.
On the other hand, as the head volume increases, the barycentric position easily shifts to the toe side. Hence, Japanese Patent Laid-Open Nos. 2010-234108 and 2011-5166, for example, disclose techniques of adjusting the barycentric position by providing a weight member. These patent literatures also disclose techniques of providing a rib to improve the strength of the periphery of the weight member.
When a weight member for barycentric position adjustment is provided, the eigenvalue of the first-order vibration mode of a golf club head changes. This means that the impact sound generated at the time of striking a golf ball changes. It is a common practice to determine the specifications of a weight member in the final stage of manufacturing a product, and design a golf club head in consideration of an impact sound before the specifications of the weight member are determined. Therefore, it is often impossible to obtain a target high-pitched sound as the impact sound considerably changes as a result of providing a weight member.